Most of the issues in ginseng at this time are related to moisture and heat stress. Tops are collapsing in areas affected by root disease, mainly because these are the areas in which the root system is not extensive enough to access soil moisture. As a result, low areas that are normally the wettest may show signs of moisture stress first. Alternaria will also develop on weakened plant material.
Gardens are also affected by both heat stress and windburn. Heat stress can be alleviated by adding vents in the middle of large gardens and/or by raising the side shades to allow air to flow through the garden. Wind burn occurs as dry air on the edges of gardens removes moisture from the leaves faster than the roots can take it up. Since alleviating heat stress by raising the side shades can lead to more windburn issues, a balance between the two may be necessary. For example, a barrier along the edge of exposed areas that is tall enough to block wind from the leaves on the edge of the garden, but short enough to allow air to flow into the garden, could reduce damage from both issues.
At this time of year, pythium often begins to affect ginseng gardens. Pythium attacks the root tips resulting in poor uptake of water and nutrients. Under dry conditions, those symptoms become obvious in a garden. However, pythium may be less active under dry conditions because it is a water mould like phytophthora. Preventing pythium may require control in May and June.